One method to offset the yellowing of white garments with age and repeated washings is to introduce a bluing agent, typically an insoluble pigment, during laundering. During laundering, if the bluing agent particles are sufficiently small and dispersed in the laundry solution, the bluing agent becomes deposited onto the fabrics and masks the yellowed color of the fabrics by partially compensating for the absorption of the short wavelength blue. The most common bluing agent is Ultramarine Blue (UMB), a water-insoluble aluminum silicate complex. Care must be taken, however, that the concentration of the blue pigment does not become so localized as to overblue a small area, thus causing a blue spot. This potential for spotting can be overcome somewhat by applying the UMB throughout the detergent or laundry additive, but this will render the product blue in color as well as causing handling problems and contaminating the manufacturing equipment, making it difficult to produce white or other colored products. One can avoid applying the bluing agent to the product base by concentrating the UMB with other low delivery additives in a separate granule or "speckle," but this may enhance the potential for blue spots to be imparted to the laundered items due to the concentration of UMB.
Prior art methods of attempting to reduce such blue spotting include formulating the speckle in a highly soluble matrix such as sodium sulfate. Others have employed a variety of surfactants, for example cationic quaternary ammonium compounds, in effort to disperse the pigments.
It has been surprisingly discovered that, contrary to the teachings of the art, blue spotting can be reduced by a speckle which has an insoluble zeolite as its base. Molecular sieve zeolites have commonly been employed in laundry detergent compositions, as a builder to provide a water-softening function when the detergent or cleanser is placed in an aqueous solution; however, the art has not taught employing such zeolites as a matrix for colorants to reduce fabric staining thereby.
Rolfes, U.S. Pat. No. 4,097,418, describes an agglomerated speckle comprising a colorant and a water soluble salt. Bloching et al., U.S. Pat. No. 3,962,116, describes heat-dried mixtures of optical brighteners and zeolites. Gangwisch et al., U.S. Pat. Nos. 4,264,464 and 4,406,808, both describe spray-dried detergents including a zeolite builder and may include a colorant.
A dry blended granular detergent component comprising a colorant and a "hydratable salt" is disclosed in Hall, U.S. Pat. No. 3,931,037. Zeolites are not disclosed as "hydratable salts." An agglomerated bluing composition is also described in Perry et al., U.S. Pat. No. 3,529,923, and comprises a water soluble inorganic hydratable salt (e.g. sodium tripolyphosphate) and UMB.
Kumatani et al., JP 59-195,221, describes a process for coating granular zeolite with colloidal silica and an inorganic pigment.
U.S. Pat. No. 4,707,290 issued Nov. 17, 1987 to Seiter et al. discloses a spray-dried granular adsorbent for adsorbing liquid ingredients for detergents. U.S. Pat. No. 4,096,081 issued Jun. 20, 1978 to Phenicie et al. discloses particles formed from aluminosilicate, sodium sulfate and polyethylene glycol, initially with about 40% water, by spray-drying, the particulate formed by the above process further being combined with a spray-dried granular detergent product for use as a cleanser.
U.S. Pat. No. 4,379,080 issued Apr. 5, 1983 to Murphy also discloses a granular detergent composition including zeolite as well as other solid and liquid components which were combined with a film-forming polymer soluble in an aqueous slurry. U.S. Pat. No. 4,528,276 issued Jul. 9, 1985 to Cambell discloses the formation of agglomerates of zeolite and silicate by addition of water and application of heat, with tumbling, for use in detergent products.
U.S. Pat. No. 4,414,130 issued Nov. 8, 1983 to Cheng also discloses agglomerates formed from zeolite, a water soluble binder, preferably starch, and a small amount of water.